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        // 圆周率 向下取整 向上取整 四舍五入版 就近取整 注意 - 3.5 结果是 - 3 绝对值 最大和最小值
        console.log(Math.PI);
        console.log(Math.floor(1.1));
        console.log(Math.floor(1.9));
        console.log(Math.ceil(1.1));
        console.log((Math.ceil(1.9)));
        console.log(Math.round(1.1));
        console.log(Math.round(1.5));
        console.log(Math.round(-1.1));
        console.log(Math.round(-1.5));
        console.log(Math.round(-1.9));
        console.log(Math.abs(-1));
        console.log(Math.abs(-1.5));
        console.log(Math.max(1, 2, 3));
        console.log(Math.min(1, 2, 3));
    </script>
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